code: def test_describe_directory(self):
      with fh.FTPHook() as ftp_hook:
          ftp_hook.describe_directory(self.path)
  
      self.conn_mock.mlsd.assert_called_once_with(self.path)
  
imports: from __future__ import annotations
  from io import StringIO
  from unittest import mock
  import pytest
  from airflow.providers.ftp.hooks import ftp
label_desc: Use image node_id 4 for calling the TestFTPHook obj's underlying member method code with example usage: obj.test_describe_directory() without return types